Often times, Indwelling catheters have widespread use for a number of medical conditions. They are used for those who are unable empty their bladders (urinary retention) or unable to hold back their urine (urinary incontinence). They may be passed into the bladder through the urethra or surgically placed into the bladder from a suprapubic location. Indwelling catheters are also used to monitor urine output, typically for post-surgical or acutely ill hospitalized patients, or to drain the bladders of patients who are unconscious. The catheter is attached to a fluid collection bag.
However, when a catheter is inserted, the bladder becomes colonized with bacteria within several days. Careful drainage of the fluid collection bag allows urine to flow freely from the bladder through the catheter and into the drainage bag. However if urine does not drain freely into the bag the bladder becomes over stretched.
The over stretched bladder causes breaks in the bladder mucosa which can allow the colonized bacteria to cause a bladder infection. Of even more concern is that an over stretched bladder can force the colonized bacteria to get into the bloodstream (bacteremia), causing fever and a severe infection. Catheter associated urinary tract infections are the leading cause of secondary bloodstream infections; about 17% of hospital-acquired bacteremias are from a urinary source, with an associated mortality of approximately 10%. In the nursing home setting, catheters are the most common cause of bacteria getting into the bloodstream.
Practitioners like to know the status of a fluid collection bag because, when a fluid collection bag becomes over-filled it will not allow any further drainage of urine into the fluid collection bag, resulting in back pressure and causing the bladder to get over distended.
Men may have incontinence (loss) of urine for a variety of reasons. One method used to stay dry is to wear an external condom catheter applied over the penis, which is attached to a urine collection bag. If the urine collection bag becomes over-filled, it can cause the external condom catheter to fall off, causing significant embarrassment due to urine leakage. There are two major reasons that the external condom catheter may fall off the penis. First, the over-filled collecting bag may cause back up of urine into the tube and stretch up the condom, pulling it on the skin. Second, the over-filled collection bag may get too heavy and pull the condom off the skin.
Another reason practitioners may want to know the status of the fluid in a fluid-filled bag is that fluid, such as sterile water or saline, may be infused from the fluid filled bag, through the catheter tubing and into the bladder to rinse the bladder to deliver medications or to prevent blood clots from forming if blood is collecting in the bladder. Not immediately replacing an empty the fluid filled bag to allow continuous drainage can allow an interruption in medications or the formation of blood clots. These blood clots can, then, obstruct the catheter, causing bladder over distention with the same problems discussed above.